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<head><meta charset="utf-8"><title>GAT questions · t-compiler/help · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/index.html">t-compiler/help</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/GAT.20questions.html">GAT questions</a></h3>

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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/GAT%20questions/near/190015495" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Areredify <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/GAT.20questions.html#190015495">(Mar 08 2020 at 14:21)</a>:</h4>
<p>First question: the GAT rfc states that adding type HRTBs is not a part of it, but also states that <code>type X&lt;'a&gt;: Y</code> is the same as <code>for&lt;'a&gt; Self::X&lt;'a&gt;: Y</code> bound on the trait itself.  I assume it means the same in case of <code>type X&lt;T&gt;: Y</code> which requires(?) type HRTBs (at least implementation wise), so I am a bit confused. <br>
Second question: I believe the rfc doesn't mention bounds on the type constructor parameters (i.e. <code>trait Trait&lt;'b&gt; { type X&lt;'a: 'b&gt;; }</code>) , although there is a line that I don't understand that is maybe related: <br>
    "This RFC does not propose allowing any sort of bound by the type constructor itself, whether an equality bound or a trait bound (trait bounds of course are also impossible)."<br>
Does that line mean that type constructor can't impose bounds on it's parameters? What about implicit bounds in type constructors parametrized by types?</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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